Bug 2540454 (CVE-2026-93828)

Summary:	CVE-2026-93828 kernel: exfat: fix handling of damaged volume in exfat_create_upcase_table()
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's exFAT file system. A local user capable of mounting a corrupted or maliciously crafted storage volume can trigger an integer calculation error when the system processes an uppercase translation table with a size of zero. This failure causes the kernel to enter an infinite loop, leading to a Denial of Service (DoS) condition.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-24 16:54:06 UTC

In the Linux kernel, the following vulnerability has been resolved:

exfat: fix handling of damaged volume in exfat_create_upcase_table()

When the size of the upcase table is set to zero in the dentry for any
reason(e.g. corrupted media or misbehaving device), an integer overflow
causes the module to loop indefinitely.

If the size of the upcase table is read zero, do not attempt to load the
table. Instead, fallback to loading the default upcase table. If the
size of the upcase table is zero or no upcase table is found, raise
exfat_fs_error() to mark the volume read-only.

Comment 1 Mauro Matteo Cascella 2026-09-28 16:05:33 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93828.mbox